We have good news and bad news. The good news is you won't have to wait long to get your grubby little mitts on the new hotness, the Nexus 4, out of Google. It'll be in O2 stores on November 13th free from £36 a month. The bad news is that if you want it on any other network, SIM-free is the only option at least for a month.
Still, when the LG Nexus 4 only costs £240, SIM-free looks like your best bet anyway. Grab the phone direct from Google, slap a cheap SIM-only contract in it, and Bob's your uncle you'll be living the Android 4.2-dream on-the-cheap.